Apparatus for producing fiber from vegetable growth materials



Sept. 16, 1947. P. G. DEUCHLER API ARATUS FOR PRODUCING FIBER FROMVEGETABLE GROWTH MATERIALS Filed Nov. 22,1941

2 Sheets-Sheet 1 L INV ENTOR 16, 1947. P. s. DEUCHLER APPARATUS FORPRODUCING FIBER FROM VEGETABLE GROWTH MATERIALS 2 Shets-Sheet 2 FiledNov. 22, 1941 X! W M R Y wp m mu. m M. P

Patented Sept. 16, 1947 APPARATUS FOR PRODUCING FIBER FROM VEGETABLEGROWTH MATERIALS Philip G. Deuchler, Snyder, N. Y., assignor toCertain-Teed Products Corporation, New York, N. Y., a corporation ofMaryland Application November 22, 1941, Serial No. 420,062

1 Claim.

This invention relates to an apparatus for producing from vegetablegrowth material fibers having particular qualities for matting andfelting purposes. The invention especially relates to an improvement inan apparatus for mechanical defibration in which individualized fibersare produced which retain all or the greater part of the encrusting andbonding substances of the original growth. The invention particularlyrelates to an apparatus for producing fiber capable of felting to form aweb of high absorptive capacity but at the same time strong andflexible.

In my co-pending application Serial No. 371,- 585, filed December 24,1940, I have described an improvement in a process of mechanicaldefibration by virtue of which the qualities of the fibers, particularlyaffecting strength and flexibility of the felt, are improved. Theprocess of said application and the apparatus of my present inventionhave particular reference to the process of mechanical defibrationdescribed in the patent to Asplund, No. 2,008,892, of July 23, 1935. Inthe process of said patent defibration is effected of vegetable materialin the form of bundles of fibers, such as chips of wood, which prior toand during the defibrating action itself is subjected to an atmosphereor gaseous medium at a temperature sufiicient to soften the encrustingsubstances of the vegetable growth. In practice steam at a pressuresufiicient to provide the softening temperature, preferably not lessthan 212 F. and normally substantially higher, is used to provide thetreating atmosphere or medium. Following this defibration step, asdisclosed in said patent, the fibers are discharged to atmosphericpressure and a suspension thereof in water, including that used forcondensing the steam and the condensed steam itself, is made fordelivery of the fiber to the paper-making machine.

In the inventive process of my application Serial No. 371,585, aftersuch mechanical defibration but while still subjected to the atmosphereof steam at a temperature preferably not reduced to a great degree belowthat of defibration, I apply a treating material, such as a chemical, toact upon the encrusting substances of the fibers to modify them so that,if desired,

these encrusting substances may be removed. Removal is not in all caseseffected but the character of the fiber is modified by such treatment.he r su t fiber is improved for certain purposes such as roofing andflooring felts because, while retaining high absorptiveness, theflexibility and the strength of the felt made therefrom are increased.This makes it possible to use the felts made of this wood or vegetablefiber in the ordinary roofing and floor covering manufacturing processesand apparatus.

It is an object of my present invention further to improve the fiber asproduced in the Asplund process or as produced in the process of myearlier application. This improvement may be carried out so as toincrease the flexibility of the fiber and strength of the felt madetherefrom over that possible with these earlier processes. Within thescope of the invention the-treatment may be carried on so thatsubstantially greater amounts of the encrusting substances carried bythe fiber as produced by my earlier process may become modified. Theymay become so modified that they may be removed asextractable materialin accordance with the extraction or removal procedure disclosed in mysaid application Serial No. 371,585 or by other known procedure. Alsowithin the scope of the invention the process may be carried on so thatfibers are secured in which hydration has occurred. The amount ofhydration may be slight or may be of substantial degree.

In one phase of the invention, following the discharge of the fiber andthe gas or steam from the defibrating machine, particularly of the typedescribed in said Asplund Patent No. 2,008,892, I deliver the gas orsteam and the fiber carried thereby to a dwell chamber in which the gasor steam is maintained at a high temperature. When steam is used it maybe maintained at a substantial pressure or may be heated to provide theatmosphere of high temperature. Preferably, in order to have thegreatest practical effect upon the fiber, the temperature of theatmosphere is maintained without great reduction below that at which thedefibration takes place.

To secure such a dwell chamber according to the invention a simplemodification of the Asplund apparatus may be made in which the dischargevalves, which are mechanically or otherwise operated in connection withthe operation of the defibrating machine, are moved to a distance and achamber of substantial volume or providing a long length of travel ofthe fiber is interposed between the discharge of the defibrator andthese valves. Within the scope of the invention, however, such a dwellchamber or space may be provided on the discharge side of the valves ofthe Asplund machine, Such a space may operate at a pressure somewhatreduced below that obtaining within the casing of the defibrator toallow for the pressure drop necessary to deliver-the steam and the fibercarried thereby through the discharge valves. In either case thetemperature of the steam may be well above atmospheric temperature andpreferably such as would be provided, for example, by steam at 100 to150 lbs. gauge pressure. The invention, however, is not limited to theparticular pressures indicated but comprises within its scope thesubjection of the fiber after defibration to an atmosphere Of a gas orof a vapor at the temperature, usually not substantially below 212F.,which is necessary to soften the encrusting substances which in theoriginal growth bind the fibers together.

For the purpose of carrying out according to the invention the treatmentproposed of the mechanically defibrated fiber, the chamber to which thefiber and gas or vapor are delivered is so constructed and arranged asto provide a substantial time of dwell therein for the fiber before itis discharged therefrom. Instead, therefore, of utilizing merely adischarge pip'e connected between the discharge valve of the Asplunddefibrating apparatus and the so-called cyclone" into which in practicethe fiber and the exhaust steam at atmospheric pressure are deliveredfor condensation of the steam and suspension of the fiber in water, Imay utilize an enlarged chamber or pressure vessel constructed so as tobe capable of confining the gas or vapor, particularly at a pressuresubstantially above atmosphere. be such as itself to afford therequisite dwell. Devices may be constructed within the chamber, however,to direct movement of the fiber while it is subjected to the gas orvapor atmosphere and to avoid accumulation thereof in piles or buncheswhich would interfere with all portions of the fiber receiving theproper treatment. Bafiles or a spiral chute or other means may beinstalled for causing and controlling movement from the inlet of thefiber into the chamber toward the outlet thereof or toward the bottomofthe chamber. Within the scope of the invention the chamber, whether onone side or the other of the discharge valves of the Asplund machine,may be provided merely by a pipe of sufiicient size and length to affordthe required time of travel therethrough from the defibrator to thepoint where the gas or vapor and the fiber shall be discharged from theapparatus for further handling.

When the enlarged chamber is to be provided between the defibratingmachine and the discharge valves thereof, this may be accomplished in asimple embodiment of the invention by removing the valves from theposition illustrated in the Asplund patent to a place at a substantialdistance therefrom and connecting them to the machine by a longdischarge pipe. Such a position, for example, may be adjacent to thecyclone" which collects the steam and fiber discharged from the machineas mentioned above. For practical purposes, however, in most cases anenlarged pressure vessel will be inserted in the discharge pipe betweenthe valves and the defibrati'ng machine. Such an enlarged chamber mayprovide for continuous movement, as above suggested, of the fiber andthe steam therethrough toward the valves while securing' the requisitedwell by virtue of the length of travel secured within the chamber. Inaccordance with the invention the gas or vapor delivered into thischamber from the defibrating machine or otherwise maintained in thischamber surrounding the fibrous material is at a temperature, preferablyThe volume of the chamber may not substantially less than 212 F., tosecure the softening of the encrusting substances on the fiber and themodification thereof.

Owing to the close proximity of the deflbrator disc casing and thedischarge valves in the normal Asplund machine no opportunity isafforded for subjecting the fiber after defibration to the action of anatmosphere of a gas or vapor, such as steam, at elevated temperature forany substantial period of time. In the process of the inventionutilizing a chamber of substantial volume or a travel of the steam andfiber through a long distance before discharge, the time during whichthe defibrated material is subjected to the high temperature atmospheremay be increased so as to be measured in minutes. Dwell to the extent of/2 minute up to 5 minutes or more may be accomplished with benefit. Inmy application Serial No. 371,585 I have pointed out that the treatmentof the defibrated material as with chemicals may be effective within afew seconds of time. While this treatment affords improvement andenables a certain amount of the encrusting substances carried by thefibers to be converted to a condition where they may be extracted, ifdesired, by suitable subsequent processes, the present invention affordsa process which makes possible such modification of the encrustingsubstances that removal of the substances may be effected even to theextent of substantially complete removal of these substances. Thisremoval may be accompanied in some cases by hydration of the fiber.

The process of the invention may be carried out in such .a way that thefiber is subjected to an atmosphere of gas or vapor at elevated tem-'peratures merely with a substantial dwell and without treatment withactive agents. It may, however, be accompanied by treatment of the fiberwith chemicals or other modifying agents, utilizing the dwell of thefiber in the chamber to make effective and to increase the, action ofthe chemicals or agents upon the encrusting substances carried on thefibers. Thus the chemical or other agent may be introduced in the samemanner as described in my prior application Serial No. 371,585 and thefiber may be discharged to the chamber of the invention and subjectedtherein to the gas or vapor for a substantial period of time. Thechemicals or agents so applied may continue their action with theresulting modification of the encrusting substances beyond that possiblewith the process disclosed in said application. To secure improvement bythe process of the invention in some cases it may be desirable ornecessary to increase the amount of chemicals or agents which aredistributed upon the fibers over that utilized in the process of saidapplication. Within the scope of the invention, however, in substitutionfor the injection of chemicals in the manner described in saidapplication or in addition to such injection, or in addition to or insubstitution for other prior art methods of treatment of the fibers orof the material from which they are produced, I may inject chemicalsinto the dwell chamber hereinabove proposed. These chemicals or otheragents, however applied, are thus afforded a substantial time to actupon the encrusting substances carried by the separated fibers or uponthe remaining portions of such encrusting substances after treatment asproposed in the prior art further to modify these substances to acondition which makes their more complete removal possible.

In another phase of the invention I provide means for maintaining thegas or vapor at the elevated temperature, particularly when a vapor isused, at a pressure substantially different from and usually greaterthan that of the atmosphere. As the Asplund apparatus operatescontinuously to discharge therefrom the steam and the fiber carriedthereby it is necessar or desirable to effect generally continuousremoval from the dwell chamber of the fiber after its modification insaid chamber. When a gas or a vapor, such as steam, is delivered to thechamber together with the fiber carried thereby at a pres-, sure whichis without marked reduction below the pressure at which defibration isefiected the dwell chamber must be made pressure tight. To accomplishthis the connection between the defibrator and the dwell chamber may bemade by means of a pipe in the ordinary manner. To effect removal of thefiber from the dwell chamdiscussion I feed into the chamber water inamounts necessary to effect within the pressure chamber the desiredsuspension of the fiber. Under the pressure of the gas or vapor withinthe chamber discharge of this water and the suspended material then maybe effected through a valve or other restriction for controlling thisdischarge. This discharge may be continuous and the rate thereof may becontrolled while maintaining the pressure within the dwell chamberrequisite for securing softening or treating temperature.

It is necessary, however, to continually replace this water withdrawnfrom the dwell chamber in order to provide water to continue effectingthe suspension of the material which is delivered into the chamber. ThisI may do by forcing water into the chamber under pressure in amountsapproximately equal to the amount withdrawn. In practice the white waterfrom the paper-making machine may be delivered by means of a pump to thedwell chamber to eifect the suspension. The

water carrying the fibers discharged from the dwell chamber may be thendelivered, if necessary with the aid of another pump, to the chest or tothe head box of the paper-making machine or to other points in thepaper-making process.

In some cases the amount of water delivered may be suflicient to effectcomplete condensation of steam, or other condensable medium when such isused as the atmosphere and'conveying medium in the Asplund process. Inother cases any excess of the medium may be exhausted through a suitablevent in the dwell chamber designed and adjusted to retain the pressuretherein.

When a non-condensable gas or vapor is used as the atmosphere medium inthe dwell chamber it may require to be vented while retaining a givenpressure in the chamber. In some cases the medium may be withdrawn fromthe chamber for reheating or replenishment to be delivered again to theapparatus at a suitable place for its reuse. In the case of a gas orvapor which is active upon the fiber or its encrusting substances theredelivery may be effected by return directly to the dwell chamber,after the gas or vapor has been suitably reinforced or regenerated toits active condition, to carry out the modification of the fiber in thedwell chamber according to the invention. In some cases, however,especially in conjunction with the Asplund process, the gas or vapor maybe returned to the Asplund apparatus to serve the function disclosed inthe patent of heating the chips or pieces of material vapor may bedelivered at the proper tempera-' ture for deflbration of the fiber orfor treating the fiber in the dwell chamber.

In some applications of the invention a condensable vapor heated to therequisite temperature may be bled into the dwell chamber to maintain theheated atmosphere therein, the vapor condensing and being withdrawn asliquid. In other cases the medium or atmosphere of the dwell chamber maybe maintained at the requisite temperature by heating the medium withinthe chamber by means of suitable heating devices installed therein.

The invention will be further understood from the description of thedrawings to follow, in which Fig. 1 shows the arrangement of the dwellchamber in connection with the defibrating machine,

Fig. 2 is a vertical cross-section of the dwell chamber,

Fig. 3 is a cross-section of Fig. 2 on line 33.

In Fig. 1 the defibrating apparatus of the type illustrated in theAsplund Patent No. 2,008,892

is shown in elevation with portions thereof broken away to reveal theessential parts which have a bearing on the invention. As described inthe Asplund Patent No. 2,008,892, through the opening 3 in the preheaterchamber 5 the chips of wood or pieces of vegetable growth material aredelivered by means not illustrated in Fig. 1 but shown and described insaid patent, Through pipe 1 controlled by valve 8 steam is introducedinto the preheater chamber 5 to maintain therein an atmosphere of steamat a pressure such as will afford -a temperature not substantially lessthan 212 F. and preferably in practice that of steam at about to 1'70lbs. pressure. The Chips received into the preheater chamber 5 fall tothe bottom portion thereof into engagement with the screw feed member llarranged in the conduit portion l3 and,rotated upon shaft l5 passingthrough stufling box I! by a suitable drive such as a chain drive 19.The shaft l5 and the screw mounted thereon are rotated in such adirection that the chips are fed into the casing 2| of the defibratorwhich carries the stationary segments 22. Mounted upon a shaft 25, inbearings 21, extending through stuffing box 29 into casing 23 is therotating disc 3| carrying segments 33.

Under the action of the screw feed member H the heated chips aredelivered to the defibrating discs and upon passing between the segmentsthereof the fiber together with the steam from the preheater chamber isdischarged through pipe 35, in which are mounted discharge valves 31 and39, into-the chamber 4|. As described in the Asplund patent steam forconveying the fiber through the casing 23 of the defibrator and throughthe pipe 35 may pass through the equalizer 36 between the preheaterchamber and the casing M of the defibrator. The chamber 4| is soconstructed, as will be hereafter described, as to provide for asubstantial time of dwell of the defibrated fiber therein whilesubjected to the steam atmosphere. The-travel of the steam and the fibercarried thereby is downwardly in chamber 4| and provision is made at thebottom portion thereof for withdrawal of theflber while maintaining theatmosphere of steam within the chamber, preferably at a pressuresuflicient to provide the requisite temperature for.maintaina 41 of thechamber 4|.

7 ing in soft condition the bonding and encrusting substances on thefiber and to secure substantial modification thereof.

In Fig. 2 is illustrated one construction of the chamber 4| for carryingout the process of the invention. The pipe 35 is connected by a flangedconnection to the top of the chamber 4| to cause the steam and the fibercarried thereby to enter the chamber and move over the topmost baifle ofa series of baffles 43 arranged in said chamber 4| These baiiies areconnected to the wall of the chamber 4| at one side thereof but do notreach the opposite side of the chamber. Between said baffles 43 arepositioned bafiles 45 which extend from said opposite wall toward theside to which the baffles 43 are connected. The vertical spacing of thebaffles and the distance between the end thereof and the wall are suchin consideration of the volume of steam and fiber delivered into thechamber that the fiber is carried by the steam through the tortuouspassage as shown in Fig. 2 between the bafiies 43 and 45 until thelowermost baille 45 is reached. Over the edge of this lowermost bafflethe fiber falls into a mass of water maintained in the lowermostcompartment Because of the tortuous passage a long travel of the fiberwhile subjected to the heat of the steam is provided which secures thenecessary time of dwell which is a feature of the invention foreffecting modification of the fiber after defibration in the defibratingapparatus. As the fiber is delivered by the defibrating apparatus in agenerally continuous although somewhat pulsating flow, it is desirableto provide for continuous withdrawal of the modified fiber from thedwell chamber 4|. To accomplish this in a suitable cylindrical portion49 of the compartment 41 is mounted an agitator upon shaft 52, extendingthrough stufllng box 53 in the end wall of the cylindrical portion 49.The shaft 52 may be rotated by suitable means, not shown in the drawing,to cause the vanes 54 of the agitator 5| to stir up and mix the fiberwith the water sufficiently to be withdrawn therewith upon dischargefrom the compartment 41. Discharge of this suspension of fiber in thewater is accomplished by control of the valve 55 in pipe 51 connected tothe compartment 41. As pressure of the steam is maintained in the dwellchamber 4| this pressure may be utilized to force the suspension offiber in the water through the pipe 51 and valve 55 into a suitablestock discharge box 59 or other receptacle or conveyor for receiving thefiber to be delivered to the next operation in the paper-making processor for other use.

In order to maintain a suitable volume of water in the compartment 41water to replace that withdrawn through the pipe 51 is introducedthrough pipe 6| controlled by valve 63 so that the infiow of waterapproximates that withdrawn through the pipe 51. A gauge glass 64 may beprovided upon the wall of the compartment 41 to indicate the level ofwater in said compartment.

At the upper portion of the compartment 41 or, if desired, at some othersuitable place a vent pipe 65 is connected, controlled by a valve 61 setto maintain within the chamber pressure of steam requisite for modifyingthe fiber but so as to relieve to atmosphere or to the stock dischargebox 59 any excess of steam or undue increase of pressure thereof. Ifdesired, at the top of the chamber 4| a pipe connection 69 controlled byvalve may be made from a supply of steam at suitable pressure tomaintain within the chamber 4| the requisite amount and pressure of thesteam in those cases where the steam received from the defibratingmachine is insufficient or at a temperature too low to be effective formodification of the fiber in the dwell chamber. The valves, 55, 63, 61and.19 in Fig. 2 are shown diagrammatically as hand.control valves. Inplace of such valves, however, automatic devices may be used, forexample, the valve 63 may be arranged as a water level control foractuation by variations of the water level in the compartment 41. Thevalve 61 may be a pressure relief valve opening only when the pressurewithin the chamber 4| exceeds a predetermined amount. Similarly thevalve 10 may be of the type which will open upon a reduction of pressurein the chamber 4| and will close upon restoration of this pressure to apredetermined amount,

Through the pipe 13 controlled by valve 15 from a suitable supply underpressure a treating agent, such as a solution of a chemical or a solventor other treating material capable of acting upon the encrustingsubstances or the fiber or both, is introduced so as to impinge upon oract upon the fiber as it is received into the dwell chamber. It will beapparent from the above description that if, for example, a solution ofcaustic soda were introduced through the pipe 13 in suitable amounts of,for example, between 2% and 8% of dry caustic soda based on the weightof the fiber, the fiber as it falls over the first baffle 43 willreceive an application of the solution of caustic soda. This fibercarrying the treating material then will move between the baffles 43 and45 in their tortuous passage and a time adequate for action thereof uponthe ligneous and other encrusting substances carried by the fiber toefiect substantial modification thereof is proyided. In consideration ofthe maintaining of the relatively high temperature in the dwell chamber,in the preferable practice of the invention this method of applicationof the treating material or of the chemical becomes particularlyeffective. If necessary to produce a full action of the chemicals uponthe fiber sufiicient water carrying suflicient amount of chemicals maybe introduced through the pipe 13 to cause continuance of the actionthroughout the length of the tortuous passage. In some cases, therefore,not only may the ligneous or other encrusting substances upon the fibersbe modified but the cellulosic portion of the fiber itself may becomechanged to afford a modified character in the fiber. Within the scope ofthe invention the chemicals or other treating agent which may be leachedin the Water contained within the compartment 41 may be recovered fromthe water discharged from said compartment or said wa ter or a portionthereof may be utilized as the vehicle for introducing chemicals orother agents through the pipe 13.

.As indicated above, in some cases it may be desirable to return to thedefibrating apparatus some or all of the steam or other atmosphericmedium which has been used in the dwell chamber for reuse in thedefibrating apparatus. In Fig. 1 is shown a pipe 89 controlled by valves8| connected from the bottom portion of the chamber 4| to the steaminlet pipe 1 at the top of the preheater chamber 5. It will beunderstood that by shutting the valve 8 and opening the valves 8| acircuit of the gas or vapor medium is established through thedefibrating apparatus,

' the pipe 35, the dwell chamber 4| and the pipe 80, which enables themedium to be reused for 9' heating the material to be defibrated priorto and during defibration and for maintaining the fiber in heatedcondition in the dwell chamber.

-If necessary to effect recirculation of the medium a. fluid circulatingdevice 83 may be placed in the pipe 80 or at some other convenient pointin the circuit.

In Fig. 1 also is shown a pipe 90 connected between the upper and lowerportions of the dwell chamber 4| to provide a circulating circuit withinsaid dwell chamber. In the pipe 90 may be connected a' suitable heater,indicated by the rectangle 9| in Fig. 1, which may be of any suitablecommon type for heating gases or vapors. Valves 92 and,93 areprovided'in the pipe 90 for shutting off Or controlling circulationthrough the circuit provided with the pipe 90 and the heater 9|.

It will be clear from the above description of the drawings that the gasor vapor introduced through the pipe I may be used not only in thedefibrating apparatus but also in the dwell chamber 4| to continue or toeffect in the latter the modification, softening or removal of theencrusting substances of the vegetable growth material or in some casesin addition the modification of the cellulosic material itself. Withinthe scope of the invention the gas or vapor medium introduced may beinert or may be active upon the fiber and it constituent materials.Recirculation of such a medium may be practiced when desired or whenconvenient or economical to do so. Especiall when an inert or inactivegas or vapor is used or when a non-condensable vapor is used the mediummay be recirculated through both portions of the combined apparatus ofthe invention and of the Asnlund patent or may be recirculated onlythrough the dwell chamber itself. In the case of an active medium inplace of the heater 9| a regenerative apparatus may be inserted in thepipe 90 to restore the active properties of the medium. It will beobvious that instead of substituting a regenerative apparatus for theheater 9| such a regenerative apparatus may be installed in the pipe 90in series with and in addition to the heater 9|.

From a consideration of the drawings it will also be understood thatre-heating of the medium, particularly of steam, may be accomplished intwo different ways in the apparatus shown in Fig. 1. Steam may bewithdrawn from the chamber 4|, for example, through the valve 93, heatedin the heater 9| and returned again to the chamber 4| through valve 92.This circuit thu may be constituted merely of the chamber 4 I, theheater 9| and the pipe connections therebetween. If necessary, animpelling device similar to fluid circulating device 83 may be includedin pipe 90.

Steam, however, may be withdrawn from the chamber 4| through the pipe 80under the impelling action of the fluid circulating device 83 and may bedelivered to the pipe 1. By suitable adjustment of the valves 8 and 8|this withdrawn steam may be mixed with fresh steam injected throughpipe 1. This mixing will re-heat the withdrawn steam. This re-heatingmay take place to the required extent to accomplish in the preheaterchamber the softening of the chips or pieces of vegetable material fordefibration in the defibrator between the segments 22 and 33 of thedefibrator. Such a method of heating may be practiced so as to maintainin the dwell chamber 4| 2. temperature suflicient to secure the softenedcondition of the encrusting substances upon the fibers so thatmodification thereof in said.

chamber may be accomplished in accordance with the invention.

Although in the Asplund patent steam is indicated as an inert gaseousmedium, within the scope of the present invention this mediumconstitutes an active medium to the extent of its capacity to effectmodification of the encrusting substances when subjected thereto for asubstantial period of time. Thus the gaseous medium used in the dwellchamber of the invention may be said to be in a condition active oractivated to effect modification of the encrusting substances or capableof efiecting such modification whether by virtue of the inherent activeproperties of such gas or vapor or by virtue of a substance or materialinjected into said atmosphere or applied to the fibers containedtherein.

Having thus described my inventionv I new claim:

Apparatus for producing fiber from vegetable growth material comprisingmeans providing a preheater chamber for confining a gaseous or vapormedium, means for delivering pieces of said vegetable material into saidchamber, means for delivering a gas or vapor medium into said chamber tomaintain therein an atmosphere of said gas or vapor at a temperaturesufficient to soften the encrusting substances of the vegetable growthwhich bind the fibers together in the pieces, means within said chamberfor mechanically defibratlng said pieces while subjected to saidatmosphere of gas or vapor substantially at said temperature into moreor less individualized fibers which carry substantially all of saidencrusting and bonding substances of the original growth material,conduit means for conveying said gas or vapor medium from said chambertogether with said individualized fibers, a dwell chamber connected atits upper end with said conduit, bailies in said dwell chamber providinga tortuous passageway of relatively reduced cross section but ofsubstantial length leading downwardly through the chamber, means forfeeding into said dwell chamber on the fibers therein steam underpressure anda chemical adapted to react with the encrusting substanceson the fibers for forming reaction compounds thereon, means formaintaining a mass of water in the lower end portion of said dwellchamber, means for stirring up the fibers in the water for enabling thewater to carry the fibers out of the chamber, means for taking steamfro-m the lower end portion of said dwell chamber and heating the steamand then returning it in heated condition to the dwell chamber near itsupper end, and means for forcing steam and vapor from the lower endportion of the dwell chamber into the upper end portion of the preheaterchamber.

PHILIP G. DEUCHLER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENT Number Name Date 1,052,675 Loomis Feb. 11, 19131,122,404 Loomis Dec'. 29, 1914 1,728,258 Sheperd Sept. 17, 19291,913,607 McMillan June 13, 1933 1,982,130 Wollenberg Nov. 27, 19342,007,348 Scharmann July 9, 1935 (Other references on following page)Number UNITED STATES PATENTS Name Date Howard May 11, 1937 KreisslerNov. 29, 1938 Ofiermanns June 27, 1939 Basler Dec. 9, 1941 Taylor Sept.2, 1879 Mason Aug. 23, 1932 Asplund July 23, 1935 Robinson Jan. 3, 1939Mason Apr. 27, 1943 Woodbridge Sept. 15, 1863 Herron June 2, 1874Blackman Sept. 13, 1887 Sammet Jan. 30, 1912 Hussey Mar. 10, 1931 EllisMar. 22, 1932 Mason Aug. 15, 1933 Hawlander 'Dec. 26, 1933 HeritageSept. 22, 1942 Number Number 15 Der Papler Fabrikant.

Name Date Beveridge June 29, 1943 Heritage Aug. 6, 1946 FOREIGN PATENTSCountry Date Australia Apr. 10, 1933 Sweden Nov. 30, 1939 Sweden Apr.11, 1940 Germany Sept. 17, 1935 Great Britain Oct. 19, 1937 OTHERREFERENCES Techniech-Wessenschaftlicher Tiel. J. G. 36-1936, pages 519to 531, Heft. 49.

Der Papler Fabrikant. Verein Der Zellstoff und Papier Chemiker U.Ingenieure. o Heft 34, pages 313 to 319.

